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NEW in SCIENCE

Sharpnel-Proof Vest is displayed by Pfc. Ralph Barlow of Redondo Beach, California. While in front line action in Korea, Barlow was hit by shrapnel and knocked to ground, but received no serious injury. Vest stopped the metal fragment.

Bell X-5 is undergoing tests at Edwards Air Force Base in California. It is our first plane able to change the sweep of its wings in flight from the most forward position, top, to a fully sweptback position, bottom, in 30 seconds. It is jet propelled.

Surfagage, precision device used by General Motors, detects scratches as small as one-millionth of an inch. It insures accuracy of finished surfaces of machined pieces and measures roughness of crankshaft, valve and precision parts in autos.

Solar Cooker is demonstrated in India’s National Physics Laboratory. The four-foot polished bowl concentrates the sun’s rays on the cooker and has power equivalent to 300 watts. It is hoped that, mass-produced, it will sell for $10 (U.S.).

Dummy Men will test new parachutes for the G.Q. Parachute Co., England, in the future. Made of steel and covered with rubberized foam, they weigh 182 lbs. and reproduce the behavior of a human body when dropped from high-altitude planes.

Bodygraph gives accurate measurements for tailoring. Felt vests of known dimensions are smoothed into place and have seams joined by photographic elastic bands. Form is registered when seams distend according to shape. D’Angelo, Paris, France.

Lubrication Platform for autos operates like a seesaw. It has a capacity of 1-1/2 tons and is adjustable for cars with wide tread. There is a clearance of four feet when one end is down. Made by Kurt George of Kasel, Germany, and sells for about $90.

Multimonica a novelty instrument, has two keyboards consisting of 41 keys each. With one it can be operated like any organ; with the other it produces tones electronically. It also has a built-in radio.

Shown at Fair in Frankfurt, Germany.

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Sun Power

SCIENTISTS for some years have been conducting surveys on the sun’s radiation, to see how it fluctuates. A daily and seasonal variation is found, separate and distinct from the seasons caused by the earth’s own motion. In the dry, cloudless regions where this is done, practically the whole intensity of the sun is received through dry, thin air; and objects placed “in the sun” become very hot. Accordingly, these men, like Dr. Abbot, of the Smithsonian Institution, or the Russian scientists working in Turkestan, have built conveniences to utilize a little of the surplus energy they are working on, for heating water, cooking, etc. The Tashkend, Central Asia, group, recently published in Russian magazines a proposal for utilizing the sun’s rays at low cost— not for electric power, but for heating rooms, cooking, and providing hot water. Tanks, with black surfaces, properly insulated, and turned full toward the sun, will heat water almost to boiling.

It is interesting to compare the proposed solar heaters, revolving to face the sun, with a project of, supposedly, the year 2660, which appeared twenty-four years ago in a novel written by the Editor of this magazine, and entitled “Ralph 124C 41 + .” The illustration, part of which is reproduced here, shows a field of sun-power devices, rotating to face the sun, in a field electrically rid of fog and moisture.

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Lightning—Man’s and Nature’s

BALL lightning, one of the rarest of atmospheric phenomena, has been seen by few people. It sometimes appeared during an electrical storm, in the shape of globes of what seemed to be like flame, a few inches in diameter, moving slowly through the air, and bursting with a loud explosion when they struck some grounded object.

The photograph at the upper right, therefore, is a most unusual one, taken recently by Dr. J. C. Jensen, physicist, of Nebraska Wesleyan University. This superball lightning approached in front of a “line storm”; the three great clusters shown appearing like a burst of skyrockets yet holding their blaze of blue-lavender light. Measurements indicated that these clouds of lightning, the largest about fifty feet in diameter, were two thousand feet away. One struck a high-voltage wire, moved along it, and then dropped to the ground. They finally exploded, leaving as usual the electrical odor of ozone.

The ball lightning evidently represents an enormously high electrical charge accumulated on dust particles, which move with the wind, illuminating the gases with which they come in contact, like that around the plate of a neon lamp, by ionization. Finally the electricity encounters a path to ground, and disappears in a violent discharge.

While the sparks of electric apparatus have been increased in length and force, by the employment of large condensers, until they seem like miniature lightning bolts, the ball of lightning has not yet been produced artificially. Nevertheless, with electric generators of sufficient voltage and power, we may consider this a possibility. Dr. R. J. van de Graaff, whose electrostatic machine, designed for atom smashing, was illustrated in the January, 1932, issue of “Everyday Science and Mechanics,” has suggested the production of huge electrostatic machines as the generators of the future.

These would produce direct current at enormously high voltages; so that the electricity could be transmitted to a great distance with far less loss than by the present systems. Such machines we must imagine running in a high vacuum, not merely to reduce air resistance, but for insulation. We are limited in the electrical pressure, or voltages, that could be built up by such machines, running in series, only by the quality of the solid insulators that could be used. (The artist has drawn for this article a machine based on the Toepler-Holtz system, well known to experimenters).

With such a generator, we might be able to make even ball lightning, and discover a use for it; as well as smash common elements into the rare ones, and produce types of radiation far more penetrating than the X-ray.

Sun Supplies Heat For This House
OLD SOL provides the heat for the hot water system in this new sun laboratory, recently completed at Massachusetts Institute of Technology for research on using the sun rays for house heating and power generation. The man on the roof is Dr. Byron B. Woertz, research assistant, who is inspecting energy collectors, or “heat traps,” in which circulating water is heated by sunlight and stored in a large basement tank for future use.

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Why Don’t We Have… SUN POWER

Old Sol has more energy than all the atom bombs in the world lumped together. And it’s free … if we can find a way to harness it.

By Frank Tinsley

EVER since James Watt built the first steam engine, inventors have been trying to harness the sun’s heat to stoke their boilers because the sun is the mightiest heat source known to man. Every hour, it floods the earth with a deluge of thermal energy equal to 21 billion tons of coal. Every day, the sun pours more potential power upon our land areas than all mankind’s muscle, fuel and working waterfalls have generated since the beginning of time.

The enormous output of solar energy is almost impossible to conceive. The sun is a monster atomic-fusion furnace, some 109 times the diameter of the earth, with a central temperature of 20 million degrees centigrade. It operates like a continuous, slow-burning hydrogen bomb generating half a million billion billion horsepower per second. As the sun is a sphere, this power radiates in all directions. Most of it flows out through interstellar space with only about half a billionth part of the total being intercepted by the earth. Of this tiny fraction, 50 per cent is reflected back into space by our atmosphere. The rest, partly reflected, partly absorbed by the earth’s surface and plant life, is potent enough to maintain our globe at a livable temperature. If this segment of solar energy seems small, it is only by comparison for it has been estimated that if all our remaining fuel—coal, oil, wood, natural gas, etc., plus the entire supply of fissionable uranium— were set ablaze in one gigantic bonfire, it could match the intensity of the earth’s solar ration for less than three days!

Modern experiments to harness this power have been many. The Russians claim to have generated steam at 875° Fahrenheit with rolled glass mirrors set in concrete. Later they reported building huge solar reflectors of cheap glass with plywood backing. These are said to have developed pressures of 30 pounds per square inch at 365°. They were designed for use in central Asia where the periods of brightest sunlight coincided with those of greatest power demand, In practice, they are reputed to have proven the practicability of generating steam on an industrial scale at any season of the year.

In the village of Mont Louis in the French Pyrenees, Felix Trombe, a solar engine designer, has harnessed the sun’s energy in the form of pure, directed heat which can melt or vaporize substances without contaminating them with chemical alloys or impurities. Trombe picks up the rays with a great, 40-foot square, flat mirror which turns automatically to face the sun. The rays are reflected into an equally large, parabolic mirror which acts as a gigantic burning glass, concentrating the heat into a focal spot which has reached temperatures as high as 4,500° Fahrenheit!

By far the biggest authenticated contraption of its kind, the Mont Louis reflector can melt 130 pounds of iron an hour and has actually burned holes in aluminum oxide—the fire resistant material used to line electric furnaces! In addition to important experimental work, Trombe’s pure solar plant will manufacture hard-to-heat ceramics out of zirconium, thorium and aluminum oxides. These will be used to coat mechanical parts subjected to intense heats, such as jet engine turbine blades, etc.

In America, Dr. Charles G. Abbot of the Smithsonian Institution, has long been the principal exponent of solar power plants. These have been of various types. Initial experiments were conducted with single and multiple mirrors of rectangular shape, curved like sections of a cylinder to concentrate the sun’s rays along the length of a tubular boiler.. Later, parabolic mirrors were tested and showed twice the heat gathering efficiency of the early types. Computations and small scale working models indicate that 20 to 25 per cent of the solar energy intercepted can be transformed into mechanical power. At this rate, 750 square miles of our southwestern desert could furnish all the electric power now required for heat, light, transportation and industrial purposes in the United States!

Abbot’s latest model incorporates a flash boiler in which water can be converted into steam within a few seconds. The parabolic mirror is mounted in gimbals so that it can turn and tilt to follow any course of the sun. Its movements are controlled by a clockwork of the type long perfected by astronomers. It automatically compensates for changes in the sun’s path over the hours, days and seasons. The mirror is assembled of concave sections of duralumin, coated with a high reflection material such as rhodium. It is mounted on trunnions and balanced with counter-weights so that very little power is required to tilt it.

The heat collection system consists of a pair of vacuum insulated, concentric tubes ending in a small, globular collector located above the center of the mirror at its focal point. A highly efficient, heat absorbing liquid such as one of the chlorinated dyphenols, is gravity circulated through the tubes. It loads up with concentrated solar heat at the collector end and carries it through the tubes to a heat exchanger mounted in the supporting structure. Here the heat is transmitted to water, changing it into steam. This is piped to a turbine which drives an electric generator. Thus, the suns rays are converted from direct heat to mechanical power and finally into electric current.

The main problem involved is the old bugbear of mirror cost. Dr. Abbot has whittled this down somewhat by building up his 50-foot paraboloid of comparatively small segments. These, to be absolutely true and uniform, must be turned out on a mammoth press using large, expensive dies. Then the mirror must be assembled on a carefully fabricated frame requiring special jigs to. accurately maintain its curvatures.

As thousands of such sun plants are contemplated, assembly line production will cut costs somewhat. Nevertheless the expense of mirror manufacture and transportation will be great, bringing the total plant investment to an uncomfortably high figure.

It occurs to me that the new Fiberglas techniques may hold an answer to this expense problem. Products with compound curvatures such as car bodies and boat hulls up to 40-odd feet in length have been cold moulded by this process. The resulting shells are light, rigid, strong as steel and impervious to weather. The moulds, also of Fiberglas, are easily produced from a plaster model. The whole production set-up can be moved from one desert building site to another,’ turning out enough mirrors for a battery of sun plants at each stand. Transportation troubles would thus be minimized.

The one-piece mirror shells, taken off an inverted male mould, would be extremely thin in section for maximum lightness. They would be reinforced on the under side by a network of moulded-on stiffeners of the same material. The resulting parabolic “dish” would combine featherweight with great strength and rigidity. The concave inside surface, sprayed with a suitable reflecting coat, would function as well as any glass or metal mirror. Such a design could well lick the present mirror headache.

The ideal solar power plant would consist of a battery of Abbot units set in a ring around a low, circular butte. Such plants could be spotted in sections of our 150,000 square mile desert area, most convenient for power transmission. They could serve industrial and agricultural communities all the way from Texas to California, complementing wind and water power plants further north. The individual plant would be almost self supporting. The center of the butte could be excavated for a reservoir, water to be piped in or pumped from drilled wells. Around this elevated pond are the necessary buildings— a bungalow for the resident engineer, storage sheds and a powerhouse for collecting and transmitting the current—all surrounded by trees and gardens.

This type of plant is extremely cheap to run. Almost automatic in operation, it requires but a single resident engineer for inspection and adjustment. Any large repairs would be handled by a central maintenance crew equipped to service a number of contiguous plants. In emergencies it could use the helicopters normally used for power line inspection. Professor H. C. Hottel of the Massachusetts Institute of Technology estimates that as much as 440,000 horsepower hours per acre can be produced in a year by such desert sun plants.

The American public has been largely oversold on the possibilities of atomic power generation. As the technical difficulties and radiation dangers of nuclear power plants gradually come to light, even the experts are beginning to cool off. Solar power on the other hand presents no such headaches. Its development problems are comparatively simple and its costs but a fraction of the tremendous atomic outlays. Moreover, the world’s supply of usable uranium is definitely limited. Sunlight, however, will last as long as our solar system. It will still be with us long after our last uranium has fissed.

As former Secretary of the Interior, Julius A. Krug remarked, “Congress would do well to appropriate a few hundred million dollars to find new sources of energy.” High on the list he placed the development of power by solar heat.

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Rubber from the SUN – and Power Too!

Amazing experiments conducted on the American desert point the way toward the day when the sun will be the universal source of power for industry—and also the manufacturing source of rubber, nitrates, and other organic compounds. This authentic article explains how such results were achieved, and describes probable future developments.

SOME day your automobile may run on rubber tires manufactured from sunlight. And some day, too, that same automobile may be driven by a solar motor, deriving its power from the energy stored up in the sun’s heat rays.

Astonishing as these statements may seem, they follow very naturally out of a series of amazing experiments conducted last summer by Dr. J. W. D. Chesney of Maywood, Illinois. Dr. Chesney is a recognized leader in this fascinating branch of science, having worked with sunlight for many years, developing a number of processes on which he holds basic patents.

How can rubber be produced from the sun? The method is explained later on in this article; the diagram on page 63 illustrates the principle. Rubber is only one of the items which Dr. Chesney proved can be manufactured with the aid of sunlight. On a laboratory scale he succeeded in making chloroform, carbon tetrachloride, and other substances through the action of sunlight on natural gas.

The idea of a sun motor is not new to Dr. Chesney. For years scientists have realized that millions of dollars worth of power is being wasted every minute in the untapped solar rays which strike the earth.

Using a sun motor only 107c efficient, the state of Arizona could furnish twice the amount of power obtained in the United States from coal, oil, and water.

If this seems an exaggeration, look at the photograph on the opposite page, which shows Dr. Chesney’s four-foot sun mirror, reproduced on this month’s cover, in action. The sun’s rays, concentrated by the mirror into a three-inch disk, burned through a piece of sheet metal in a few seconds.

Storage Method Is Problem The greatest difficulty in the utilization of solar energy for power lies in the lack of suitable storage methods, so that energy can be piled up for use on rainy days and at night. This is by no means an insurmountable difficulty. Dr. Chesney proposes a system in which certain liquids of high boiling point are heated by the sun and the heated liquid stored in modified Dewar flasks, to be called on as needed.

There is nothing fantastic in this idea. In an experimental plant which was con- structed, thin metal tubes were passed through the hot liquid. When water was poured through the tubes, heated by the liquid, it was transformed into steam. Still another storage method would be to convert solar radiation into thermo-electricity by concentrating sunshine on hot junctions and charging storage batteries. This stunt has actually been done in Chicago. Sunlight concentrated on hot junctions, 100 pairs, produced enough electric current to charge a 6-volt storage battery or to run an electric motor which operated small toys.

Sun Generator Will Come The world awaits a thermo-electric generator; some day it’s bound to come, for present sources of power—coal and oil— are definitely limited. Within a comparatively few years they will be entirely exhausted. Considering these facts, it is amazing how scientific research has lagged behind in this field. Dr. Chesney is convinced that if a small fraction of the money now used in attempts to smash the atom were expended on sun power development, the power question would be forever solved. Suppose, for instance, that you could harness and store the sunshine that falls on the roof of your home. Assuming that you have an average bungalow, 30×40 feet, the amount of sunlight that falls on the 133 yards thus represented equals 220 horsepower—roughly equivalent to the power of four average motor cars, as illustrated in the accompanying drawing. Why, then, are you buying coal, gas, and electricity?

No less interesting than the power possibilities of the sun are its photosynthetic abilities (meaning the capacity of building up compounds with light).

We have already mentioned rubber as being manufactured in this way. Let’s see how Dr. Chesney did it. First he constructed a chromium-plated cylindrical reflector, illustrated herewith, which concentrated the sun’s rays on a fused quartz tube. Quartz was used because it transmits the sun’s ultra-violet rays.

Then he passed a mixture of acetylene and hydrochloric acid gas through mercuric chloride (a catalyst) and vinyl chlorid was formed. Vinyl chlorid, when exposed to the shorter rays of sunlight in the presence of certain uranium salts, is converted into caoutchouc chloride. Caoutchouc is raw rubber, which remains after the chlorine radical is removed from the compound.

Dr. Chesney reports the process of manufacture as very simple, but, because of price, not commercially feasible at present.

Sun chemistry is not a mysterious science. You yourself, if you have ever taken a snapshot with a camera, have performed a successful experiment in sun chemistry, in which refracted sunlight, acting on the sensitive emulsion of plate or film, changed one silver salt into another and thus produced a photographic negative.

Design of Solar Reflector There was nothing in the least complicated about Dr. Chesney’s apparatus. The reflectors used in his sun chemistry experiments can easily be built by almost anyone. Sheets of chromium-plated copper were fastened to a wooden base, as shown in the photographs on this page, producing such a high concentration of solar energy at the focus that it was necessary at times to use water-cooled cells to avoid burning up the end products of the experiments. Temperatures of 2000 to 3000 degrees centigrade were easily obtained by concentrating sunlight.

At this temperature it is possible to make nitrates from the atmosphere. Oxygen and nitrogen from the air is caused to unite at this heat, and if cooled very quickly will dissolve in water as nitric acid. It is difficult to over-estimate the importance of this particular process when one remembers that nitrate fertilizer is the only means of restoring the productiveness of farm land exhausted of its mineral riches through constant use.

Making Chloroform From Natural Gas With this same type of apparatus natural gas was caused to combine with chlorine under action of solar radiation, producing chloroform and many other compounds. Thus far the process has only been conducted on a laboratory scale, but all great chemical discoveries start in the laboratory and are later expanded to commercial proportions. The great American southwest, with its perpetual sunshine and burning deserts, may some day be dotted with hundreds of factories using the sun not only as a source of power for moving their wheels, but also as the prime mover in the process of manufacture.

Sun Baths Taken Internally Sun baths have in recent years become a popular health fad. The ultra-violet rays of the sun convert the ergosterol of the skin into vitamin D, which passes into the circulation and brings about the utilization of certain minerals. Knowing this to be true, Dr. Chesney’s staff attempted to convert ergosterol into vitamin D with natural unconcentrated sunlight. Ergosterol was dissolved in various solvents and exposed to the sun.

In every case success was attained in getting activation in some slight degree, but not in sufficient concentration to make it a commercial feasibility. Refinements now being conducted indicate that the day may come when, instead of exposing our bodies to the sun, we may achieve the same health results by adding a concentrated vitamin source to the diet.

To return to the power possibilities of the sun, one of the photographs on this page shows an experiment which you can easily duplicate if you are skeptical. The direct rays of the sun, streaming through a basement window, struck a reflector and were focused on the hot junction of a Cenco thermo-electric magnet. In a few minutes sufficient electricity was generated to hold up a bucket containing 100 pounds of pig lead.

In a variation of the experiment, under the same condition, sun coming through the window was concentrated on the slit of a thermocouple, and the current produced detected on a galvanometer. With 25 couples a small electric motor was caused to run. Any experimenter can perform part of this feat if he has a delicate galvanometer, a parabolic mirror, and a small amount of copper and wire for thermocouples.

Checking the accepted figures which give the solar constant as 1.7 horsepower per square yard, Dr. Chesney found the total to average slightly higher than this. Reduced into terms of dollars and cents this means that every second $478,000,000 worth of solar radiation is wasted.

Sun Furnace May Vaporize Diamonds
A HEAT of 4500 degrees centigrade, intense enough to turn a diamond into vapor and to melt any known substance, is expected to be generated in an amazing new solar furnace which derives its heat directly from the sun. Eighty per cent of the sun’s heat is expected to be captured by the furnace, which has been designed by scientists of the California Institute of Technology in Pasadena. It consists of a mounting similar to that of a telescope which always follows the sun, upon which are 19 lenses which focus the sun’s rays on a central spot within the apparatus.

Solar cells on top of helmet power a tiny transmitter and receiver during daylight. The silicon cells also charge four small storage batteries to operate the set at night. (U. S. Army Photo)

Big Bee-hive Gets Water From Air

AN ODD “drinking water fountain” in Europe acts as a giant artificial spring, condensing the moisture of the air.

The thick brick walls keep the inside of the stone structure at a lower temperature than the outside, so that moisture condenses on the thousands of stone slates.

Leg Power replaces electricity in this Parisian beauty salon, where Madame has her hair dried despite the lack of coal-generated current. An ingenious beautician hires unemployed 6-day bicycle racers to peddle away on a bike, the back wheel of which is attached to a small generator! The current runs 6 driers.

Urge Alcohol Gas for Farm Relief

FOR economic and technical reasons a mixture of alcohol and gasoline for automobile fuel is being recommended by farm relief advocates.

Use of the fuel by motorists would consume 680,000,000 bushels of corn a year, greatly reducing the crop surplus, it is said. The gasoline would be diluted with 10 per cent of alcohol. It is claimed the fuel results in greater power at considerably less cost.

Midwestern farmers, seeking adoption of the fuel, claim that it has a higher antiknock value, will start the motor more readily, give a faster pickup, form less carbon, will not increase oil dilution, and results in a cooler engine than ordinary gasoline.

The fuel, they say, uses a greater volume of air and burns more evenly in the cylinders.

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HOT NEWS ABOUT THE SUN

Not in the future—but right now—scientists are putting to work the limitless energy of the sun.

By Lester David

SOON, a native of East Punjab, India, will walk into the local version of the neighborhood hardware emporium, plunk down 80 rupees and buy a newfangled kind of stove. Back home, he’ll proudly unwrap the shiny gadget, set it up and tell his wife to start dinner.

Less than an hour later, she’ll call out the Indian equivalent of “Come and get it!” and the family will sit down to a meal—a meal cooked by sunshine in the world’s first mass-produced solar stove!

This initial Solar Cooker—a device simple to operate, easy to maintain and economical to use—is actually in production in India right now and is just about ready to go on the market.

This development has great significance, for two big reasons:

1. This and other recent forward strides in solar energy—the harnessing of the sun’s limitless power for the needs of man—now open for the first time exciting commercial possibilities.

2. Despite what you may have thought, sun power is no longer a phantom, will-o’-the-wisp notion chased vainly by a few starry-eyed inventors. It is actually here!

Let’s dig a bit deeper into the opportunity aspect.

Last Fall, the National Industrial Conference Board brought together a group of businessmen in New York City to thrash out the question of just how the sun’s great energy, free but elusive, could be trapped for commercial use. One of the chief speakers was octogenarian Charles G. Abbot, secretary emeritus of the Smithsonian Institution in Washington and a world-famed astrophysicist. He jolted the assembled businessmen with this: “There is a world-wide demand for small solar-power machines, up to five hp, for irrigation, heating and cooling of dwellings, charging batteries and other ranch uses. The demand is very keen in Australia, India, Israel and other semi-arid regions where fuel is several times more expensive than in the U. S. At present there is no company manufacturing such units, though the demand is large and constant.”

Dr. Maria Telkes of New York University, one of the world’s foremost authorities in the field, also spoke to the businessmen and outlined what’s ahead. Hear this: Small household appliances utilizing the power of the sun will be in wide-spread use soon, Dr. Telkes said. She expects them within the next five years! “Especially in tropical regions where conventional fuels are at a premium,” she pointed out, “small devices powered by the sun can soon be a reality. …”

What else is coming? “Small cooling units utilizing the sun’s energy are also feasible,” said Dr. Telkes.

And still a third foreseeable application, she asserted, lies in development of small-scale thermo-electric generators for household purposes.

A fourth possibility is the use of the sun to convert sea water to fresh water for human consumption and irrigation purposes, thus opening up vast new areas to habitation and cultivation.

The authoritative Wall Street Journal, which keeps its fingers closely on the pulse of opportunity, predicts that a few manufacturers will “plunge headlong into the sun-stove field in the immediate future.”

“Though the stoves have been tested on a laboratory scale,” the Journal declared in a recent report, “there are still problems to be solved before they’re likely to be produced on a mass scale. Scientists hope, however, that if some manufacturers get stirred up about commercial possibilities, the resulting research will speed the arrival of practical solar energy units.”

Let’s look now at what’s actually going on in solar energy. Enormous work costing huge sums still remains to be done, of course. But the really big story is that scientists, working in many dozens of university laboratories and research foundations throughout the world, have finally struck pay dirt. They have made the first significant beginnings and learned some of the precious secrets of capturing energy from Old Sol.

Take the Solar Cooker which is on the production lines in teeming India. It was developed by that nation’s National Physical Laboratory after years of research and permission has been granted to a firm called The Jeevanlal Limited in Calcutta to produce it on a mass scale.

The stove consists of an aluminum sheet about four feet wide which is pressed into a concave shape and is brilliantly polished to reflect the sun, acting as a lens to gather heat. In the center of this mirror is an opening from which protrudes an attachment to hold a “burner” on which a cooking utensil is placed.

The mirror is supported on a cast iron frame and can be revolved in the direction of the sun to extract the maximum possible heat. The cooker itself is designed to serve a family of five, weighs only 30 pounds and has the heating capacity of a 400-watt electric oven.

Researchers who conducted numerous tests in all sections of India discovered that vegetables could be done to a turn in 25 minutes in sunlight of 105° F. Rice required 33 minutes. They found, too, that in dry regions such as East Punjab, Madhya Pradesh and the deserts, the stove can be used for fully 310 days of the year. Because of some wet and foggy intervals, it can be put to use slightly less in Bombay and parts of South India, but even then the natives can cook with sunlight about 285 days annually.

The stove, which costs 80 rupees or about $16.80, is expected to save the government of India about $42,000,000 each year in foreign exchange used now to buy kerosene and stoves from other countries. And the natives are jubilant —they save on fuel bills, there is no flame and hence no danger of fire, there is no smoke and hence no discolored walls and there are no ashes and hence no troubles about cleaning.

The stove is certainly ingenious and a milestone in progress, but for some- thing truly amazing consider the scientific bombshell exploded only a few months ago—the creation of the world’s first solar battery—first successful device to convert useful amounts of the sun’s energy directly and efficiently into electricity!

This remarkable device was developed at the Bell Telephone Laboratories in Murray Hill, N. J., by a team of three scientists, Gerald L. Pearson, Calvin S. Fuller and Daryl M. Chapin. Even as presently constituted, they ‘ pointed out, it is vastly superior to the recently developed atomic battery as a source of fuel power. The latter produces only one millionth of a watt of energy—the sun device can deliver power at the rate of 80 watts a square yard of surface.

It has been improved, too. When first announced last April, the battery had achieved what scientists call a six per cent efficiency in converting sunlight directly into electricity. Other photoelectric devices have never been able to get above one per cent. By October, however, Bell experts created cells which yielded a record eight per cent, comparable to those of steam and gasoline engines. Moreover, nothing is consumed or destroyed in the energy conversion process, and there are no moving parts, which means that the battery should last indefinitely.

The sun battery is actually an amazingly simple apparatus using strips of silicon about the size of razor blades. These wafers are linked together to deliver power from the sun.

The key to the technique lies in the special treatment Bell scientists give to the silicon wafers. First they remove all the impurities in ordinary silicon, then carefully introduce a foreign element into a microscopic layer near the surface. This renders the silicon disk extremely sensitive to light.

Did you know that there are now a number of sun furnaces in full operation, heating, burning and melting for science ?

The world’s largest is atop Mont-Louis, in the French Pyrenees, and was established not long ago by the French Government. An ancient fortress was * converted into a modern solar energy laboratory and the sun furnace, which can produce an intense heat of 5,432° F, was installed.

Hot? One skeptical visitor entered the grim citadel one overcast day recently and said, in effect, show me. A technician did. He swung one end of a massive steel bar into the furnace and even though the big baby was operating far below its maximum temperature, the steel instantly turned white hot and started to melt. “It was so brilliantly radiant,” the visitor admitted, “I had to watch it through smoked glasses.”

The apparatus consists of two enormous mirrors—one a stationary parabola with a 105-square-yard surface, the other a larger flat mirror that follows the sun like a mechanical sunflower and reflects its rays directly into the parabola.

The parabola reflects these incoming rays to a single focus. Consequently, the sun energy is concentrated tens of thousands of times into a minute space. Intense heat results.

The French solar furnace is doing important work in producing and studying a class of minerals called high refractories, which are prepared and fused at temperatures too high for ordinary mineralogical furnaces.

America creates some pretty high temperatures on its west coast. Consolidated Vultee Aircraft Corp., for instance, operates a solar furnace at San Diego, Calif., and it’s quite a warm little thing in its own right. Convair is experimenting with metals to go into jet and rocket engines and in guided missiles, and it’s looking for substances which can stand more heat than any uncovered so far.

This instrument has a 120-inch aluminum mirror formed into a parabolic reflector. The sun’s rays are collected and shot to a focal point about the size of a dime and this hot spot is hotter than an oxyacetylene torch at full blast.

What’s the score on sun-heated houses? Again, science is farther along than you thought and again, some aspects are actually here already!

Hear the authorities: A report by the President’s Materials Policy Commission estimated recently that there would be fully 13,000,000 solar-heated homes in America by 1975. Dr. Farrington Daniels, of the University of Wisconsin, a past president of the American Chemical Society, believes that the most promising immediate use of sun power lies in house-heating.

R. S. Dill, chief of the heating and air conditioning section of the National Bureau of Standards, asserted not long ago that solar heating of homes has been satisfactorily demonstrated.

Some evidence: In Florida, Texas, Arizona and California, the use of solar energy as a means of producing domestic hot water has made a good deal of headway. In these homes, a network of pipes is mounted on the roof and exposed to the sun under one or two layers of glass. Then the sun-heated water, at a temperature of about 150° F, is stored in an insulated tank for use whenever the homeowner wants to turn on the tap marked “H.”

Two houses with complete solar heating equipment have been built for experimental purposes by scientists of the Massachusetts Institute of Technology and show possibilities that are more than promising.

One is located at Cambridge, Mass., and was constructed under the supervision of MIT’s Dr. Hoyt C. Hottel. It has four rooms and a sloping south roof covered by a glass-enclosed metal plate that acts as a heat collector. Water warmed by contact with this collector is pumped into a 1,200-gallon tank mounted in the attic. From there, the hot water is circulated throughout the house. There’s one drawback, however—there isn’t always a uniform interior temperature.

The second house at Dover, Mass., sought to hurdle this barrier. This dwelling has solar collectors on its vertical south wall. Warmed air is then circulated down to a basement bin filled with a compound called Glauber’s salt. The warm air melts the salt crystals and in so doing the latter absorb generous quantities of heat.

Comes evening or a cool day, and the salt solidifies. As it does, it releases its stored heat into water, which circulates into the house’s radiators.

The salt never needs to be renewed.

What else do we already have? For one thing, the armed forces are using small solar stills in emergency equipment. These devices are on life-saving rafts and are designed to make salt water drinkable.

And now just one final thing. Are you interested in elbowing into this vast field? Then listen: I asked Dr. Telkes of New York University what advice she had for those who wished to know more about solar energy. A good engineering course of study, was her reply. How about books on the subject? Dr. Telkes suggests these books and periodicals: Books: Energy In The Future, by Palmer C. Putnam, published by Van Nostrand Co., N. Y.; Energy Sources—The Wealth Of The World, by Eugene Ayres and C. A. Scarlott, published by McGraw-Hill, N. Y.

Periodicals: Future Uses Of Solar Energy, in Bulletin Of The Atomic Scientists, Vol. VII, Nos. 7 and 8, August 1951.

Fresh Water From Sea Water By Solar Distillation, in Industrial And Engineering Chemistry. Vol. 45, May 1953.

A Review Of Solar House Heating, in Heating And Ventilating, Sept. 1949.

Space Heating With Solar Energy, in The Scientific Monthly, Dec. 1949.

A complete bibliography on the uses of solar energy, Dr. Telkes asserts, has been prepared at the Stanford Research Institute in Stanford, Calif., and is now available.

Dip into some of these and see what’s cooking with solar energy. You’ll find the fog is clearing away and the rays are shining through—rays, untamed until now, which will eventually provide mankind with limitless sources of energy. That’s why science, right now, is all hot and bothered about the sun.

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NOVEL NEW MACHINES for PULLING POWER from the SKIES

IN THE endless quest for cheap sources of energy, two proposals have recently been advanced which demand serious consideration, both for appeal to the imagination and the possibilities of practical operation.

The high speed windmill shown on this page is the latest development of Volf’s laboratories in New York. The first of these power producing units will be in operation by May first. Three fans are provided so that one is always facing a wind current. The fans are geared to a gyro stabilizer which runs on inertia so that the fans will not run down in calm intervals between gusts of wind.

A generator is driven by the geared shaft, producing current for storage batteries. In actual practice three or four small generators will probably be used, one or more of them being automatically cut out when wind velocity falls below a certain point.

Another idea, less close to realization than Volf’s windmill but involving natural phenomena just as dependable, partially owes its inception to the stratosphere balloon ascents of Prof. Auguste Piccard. The extremes of temperature encountered by Piccard, in which the outside air was around 75 degrees below zero while interior temperatures of the gondola were around 100 degrees, makes possible the operation of a thermal engine as described in detail on opposite page.

Sun’s Rays Harnessed to Run Steam Engine

One of man’s great ambitions— to harness the sun to a steam engine—has been achieved. Dr. C. G. Abbot, secretary of the Smithsonian Institution, has developed a solar heater and demonstrated that it would operate a one-half horsepower steam engine with sufficient efficiency for commercial purposes. The sun’s rays are his fuel. Caught in three parabolic cylindrical mirrors of sheet aluminum, the rays are reflected in high concentration upon tubes of Pyrex glass. Passing through two concentric tubes of glass respectively one and one-fourth and seven-eighths inch in diameter, the rays reach a central one-half inch Pyrex tube which is metal plated on top and contains a black chemical, a chlorinated diphenyl compound to which a small amount of lampblack is added so that the liquid absorbs virtually all the sun’s rays. Although liquid at ordinary temperatures, it still does not boil or flash at 662 degrees Fahrenheit. Between the concentric tubes a vacuum is maintained so that the heat of the liquid is retained. Superheated, this chemical is circulated through pipes to a boiler where it generates steam. Experimentally, this solar heat engine had an over-all efficiency of fifteen per cent in producing steam power. Dr. Abbot believes the time may come when, with coal and oil supplies dwindling, sun power may become essential. Even with the apparatus available today, he says, the sun can be harnessed for cooking, refrigeration, evaporation and small power plants. Ranches and communities in cloudless regions are manifesting interest in development of sun power.

Inflatable Solar Collector

Rocketing into space in a canister the size of a teacup, a solar collector will billow out to a conical shape with a metalized Mylar reflector that is seven feet in diameter.

The sun’s rays striking the reflector are focused onto a collector. These rays will be transformed into heat energy which then may be used to power various electrical and mechanical instruments in space.

Under tests by the G. T. Schjeldahl Co., Northfield, Minn., the collector is held to precise dimension by a rim inflated to five pounds per square inch of pressure.

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ROOF-TOP HEAT TRAP STORES POWER FROM THE SUN

HEATING homes in January with the warmth of last summer’s sunshine —that is the exciting goal of research now under way at Cambridge, Mass. Not far from the Charles River, scientists of the Massachusetts Institute of Technology recently completed a white frame building, its sloping roof edged with a glistening battery of solar-heat traps.

These cells are formed of “sandwiches” of glass sheets, air spaces, and metal plates. The rays of the sun penetrate through the sheets of glass and strike a black metal plate at the bottom of each cell. It absorbs heat rapidly and the dead-air spaces between the glass panes act as insulators and keep the heat from dissipating outward. Beneath each metal plate, a maze of thin-walled tubes carries a flowing stream of water which is heated by contact with the metal and then conducted to an efficiently insulated storage tank in the basement of the building. Hot water can be stored in such tanks, it has been found, for weeks and eventually it is expected that “sunshine furnaces’ of the kind will be able to hoard summer heat for midwinter use.

For more than twenty centuries, experimenters have been striving to store up summer heat and trap the endless flow of power from the sun. Recent efforts to crack this age-old scientific nut range from Dr. C. C. Abbot’s solar furnace to the “sunshine sandwiches” of Dr. Bruno Lange, of Berlin, Germany. His photo-electric cells generate current when struck by the sun’s rays. Other experimenters have employed mirrors, titled by clockwork, and giant lenses, concentrating heat to melt metals.

Contracting Wires Harness Sun’s Rays

THE long, exhausting search of scientists for a method of harnessing the rays of the sun has yielded the solar machine illustrated in the artist’s drawing above.

Operation of the machine is based upon the principle of contraction and expansion of tungsten wires. These wires are arranged lengthwise of a revolving drum, and the sun’s rays are directed against them by means of a parabolic mirror on each side.

As the drum rotates the wires pass out of the focal range of the sun’s rays and are doused in a trough of water at the bottom. Sudden cooling of the wires causes them to contract rapidly, pulling on a bell crank at the end of the drum. This action in turn causes the dogs to engage notches in the fixed ratchet and drive the drum around. Rotation of the drum causes the shaft to which it is fixed to revolve and operate the pulley on the same shaft. J. J. Warner, of San Francisco, is the inventor.

CHINESE WINDMILL WATERS FARM
Adapting an Oriental idea for raising water for his own needs and to irrigate his fields, a California farmer has constructed the curious apparatus shown in the accompanying photographs. Power from a windmill, transmitted through gears, revolves a spiral-shaped tube of pipe open at both ends. The outside end dips into a water-filled ditch at each revolution. Water is thus picked up, and runs by gravity around the spiral to the hub as the wheel revolves. An opening in the hub dis-charges the water into a trough four feet above the level in the ditch, giving a sufficient lift for the irrigation purposes desired.

SUN’S RAYS ARE HARNESSED IN SOLAR FURNACE

ARCHIMEDES, famous mathematician, is said to have set fire to the fleet of the Roman emperor, Marcellus, by the use of a series of concave mirrors concentrating the sun’s rays upon the fleet. John Ericsson, the designer of the Monitor, of civil war fame, constructed several engines having boilers provided with mechanical devices for effecting the necessary concentration of solar rays which, when collected from 100 square feet of surface, effected the evaporation of 489 cubic inches of water per hour, more than equivalent to one horsepower. This is, however, but a small proportion of the potential energy actually developed by solar heat hourly received upon an area of this size. Ericsson estimated it to be equivalent to that caused by the combustion of 200 tons of coal in the same time. To harness this energy, a solar furnace, with which it is claimed it is possible to attain much higher temperatures than that given by the electric furnace, has been built. The apparatus is composed of about twenty-five lenses and mirrors, the mirrors forming the walls of a cone and the lenses arranged to form a dome near the base of the cone. By adjustments the sun’s rays are concentrated within an area of about one-quarter of an inch, which is the working part of the furnace. It is claimed that by simply increasing the number of lenses and mirrors increased temperatures may be attained. In tests made with this furnace, the more common metals immediately melted and passed off in gaseous form. Even substances like graphite are unable to withstand the intense heat. The working part of the furnace is, of course, extremely small and can handle samples of not over two grams in weight. One of the advantages claimed for this . apparatus is that substances can be melted or evaporated in a vacuum, as they may be inclosed in a glass vessel. It is believed that a furnace of this sort can reach temperatures sufficiently high to melt substances that up to the present have been considered infusible.

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Giant Wind Turbines

Currents in Upper Air Form Unfailing Source of Power for “Windmills” of Future

WIND, at the surface of the earth, is proverbially uncertain; but recent researches show that, a thousand feet or more above the ground, wind is comparatively steady and unfailing. This has given new life to the hope of finding a substantial source of natural power, even more universally available than water power; and the designs illustrated here have been prepared by a German engineer, Honnef, the erector of several huge radio towers. As shown here, the structure carrying the power plant would be higher than any other building man has yet been able to erect.

The surveys which have been made in Germany show that, with little variation, wind velocities of 22 miles an hour are quite constant at the height illustrated. To utilize this most effectively, instead of small wheels, it is proposed to erect on each wind-turbine tower three power wheels, each 530 feet in diameter. The whole weight is so counterbalanced on bearings that it faces the wind; while the angle at which the wheels encounter the air currents is depending upon the velocity of the wind. If this is very high, as in a storm, they present their edges only; if the currents of air are light, the wheels take a vertical position, as illustrated in the detail at the lower right of our illustration. The wheel will begin to rotate in a breeze of but 4 miles an hour and, because of its great inertia, will turn steadily.

The method of generating the power is unique. Instead of gearing the great wheels to a generator, as in previous construction, each wheel is itself made the rotor of a great electrical generator. The rings are double; the armature and field coils are built into the outer and inner rings, respectively; and the output is fed into a distributing system, which has the necessary transformers and converters. The inventor plans 40,000-volt direct-current transmission lines. The cost of each 30,000-horsepower unit is estimated at $1,100,000; delivering 130,000,000 kilowatt hours a year with slight cost for maintenance.

The first experimental tower to be erected is to be 665 feet high, with 200-foot turbine wheels, and located near Berlin.

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Putting Nature’s Power to Work

Methods of Harnessing Natural Energy Described by DICK COLE

Upward of 40,000 inventions a year are granted patents by Uncle Sam, but not one of these offers a practical solution of the problem which scientists agree is the most pressing of them all— that is, how to harness natural sources of energy for power. Mr. Cole does not profess to have solved the problem, but the methods he describes here point out the trend of probable development.

WHAT is the most needed invention? Not television—not new kinds of airplanes—not speedier automobiles. Men of science are agreed that what the world needs most is a motor which converts the sun’s rays and other forms of natural energy into usable power. Orville Wright, Lee De Forest, Elihu Thomson, and other leading scientists are among those who proclaim the need for a new motor.

There are two sources of inexhaustible energy which at once occur to the inventor —wave or tidal power, and solar rays. A. Los Angeles inventor has developed a wave motor—an “inertia” motor, he calls it— which gives promise of being developed into a practical commercial project.

Scores of so-called “wave motors” have been built in the past, but none has proved a conspicuous success commercially. Usually the initial erection cost and the maintenance cost has been out of proportion to the results obtained. And, too, the force of a storm has been underestimated, and the first severe gale completely wrecks the machine.

The new “inertia motor” is absolutely storm-proof—in fact it could outride a tidal wave. And, too, it is the acme of simplicity —it requires no foundation, and has no connection with the ocean bottom except by its anchor chains.

A study of the accompanying diagrams makes it clear how the inertia motor operates. If you are mechanically minded, you will be impressed. The application of the name “inertia” will be obvious. When a wave starts to lift the hollow sphere, the massive weight inside, because of its inertia, resists the movement and exerts terrific pressure in the lower cylinder. Finally the inertia of the weight is overcome. Then it possesses momentum. When the sphere reaches the crest of a wave, the combined effort of the momentum and the recoil of the huge, semi-elliptic springs exerts an equal pressure in the upper cylinder. The tremendous pressure is applied to oil, which, in turn, operates a special turbine which runs a generator. The current is conducted to the shore by submarine cable.

The idea seems wholly practical. It is readily conceivable that a battery of “inertia motors” could be built into an elongated float set parallel with the wave movement, and power in unlimited quantities would be available.

The cost of building these motors would not be excessive—the maintenance cost is almost nil—the storm hazard is eliminated. Collision is the greatest hazard, but this is hardly worth considering as the float would have “running lights” at night.

A conservative estimate of the cost of the complete installation, except batteries, indicates that the value of the current generated, at 5c K.W. hour, would equal the installation cost in 18 months.

The power available from ocean waves is unbelievably huge. Suppose a wave comes along and lifts a 25,000-ton ocean liner 10 feet in 5 seconds. How much power is expended? The 25,000 tons is equivalent to 50,000,000 pounds; which, raised 10 feet, represents 500,000,000 foot pounds. Since this work is performed in 5 seconds, the amount done in one minute would be six billion foot pounds. One horsepower is that required to perform 33,000 foot pounds per minute, so simple division gives the wave’s horsepower as 181,818!

Every day in the year the sun is dissipating incalculable, immeasureable energy upon this earth of ours, energy which can be brought directly under control for immediate use, instead of waiting for a new geological era to make it available. The trapping and utilization of solar energy is not new—”solar engines” have been built before—but direct, commercial application of solar energy for power conversion has not been achieved.

An idea for a sun-power plant, illustrated in these pages, seems to be in a fair way to achieving success. A drawing shows the theoretical working of the solar power plant. One side of the unit is a tank containing water, heat insulated on all sides. On top of the tank is a shallow basin of greater area than the cross-section of the tank itself. This basin is covered with a layer of sheet copper providing a space of about one inch within the basin. Water from the tank enters the basin at the center point and spreads out to the rim where it is returned to the tank.

The top of the copper covering is painted flat black. Obviously when this tank is exposed to the glaring sun, the black surface absorbs the heat which is communicated to the water in the shallow basin. The entire mass of water is sealed from the atmosphere, and evaporation, which would tend to cool the water, is prevented. The thin layer of water becomes very hot and is carried into the main tank. The circulation goes on and on, constantly building up the temperature in the main tank. The heat insulation prevents radiation losses. In a working model, the temperature was built up to 180 degrees.

We have now established a mass of hot water. Now for the cold element. The tank at the right is the same volume and is insulated the same as the “hot” tank. In this case the water is circulated to an evaporation cooling system. This consists of a shallow upper tank from which are suspended many sheets of a special flax fabric such as desert water bags are made of. The water trickles down these. This cooling system will maintain the temperature of about 60 degrees in the cooling tank.

Apparatus Runs Automatically

We now have established a heat differential of nearly 100 degrees. The boiler and the condenser are an innovation. Note that each is set in the water of their respective tanks. The system is synonymous with placing a conventional boiler in a mass of molten lava. The boiler-condenser system is partly filled with pure, distilled water. The initial vacuum is established by injecting live, super-heated steam into the system. Then the cocks are closed, and when the steam condenses a permanent vacuum is established. Thereafter the boiler vaporizes a vast amount of water; the condenser liquefies the vapor; an injector pump returns the water to the boiler; an eternal cycle going on continuously, while between the two, a low pressure steam turbine converts the energy into terms of kilowatts.

Let us now transpose our theory into commercial terms. Southern California offers some ideal locations for a solar power-plant. Almost any point along its coast would meet the physical requirements, but Salton Sea, at the north end of Imperial Valley, is most ideal. Here the mid-day sun gives rise to temperatures of 110 to 120 degrees. And, too, the air is very dry which adds to the efficiency of the cooling system.

Construction Cost Moderate

The initial cost of erecting a power-plant like this would not be prohibitive. Even if it cost twice as much as a conventional steam plant of the same power output, this would be more than offset in several years by lower upkeep cost. The solar plant could be made so automatic in operation that it would require practically no attention.

Practically the only upkeep cost of this solar distillation plant is for fuel for a small gasoline motor which operates two pumps; one for pumping the distilled water to the storage tank, and the other for maintaining the salt water in the evaporation basin. A surplus of water must be provided to the evaporation basin to prevent crystallization, and, too, the basin must be thoroughly flushed out occasionally.

Still a third apparatus, deriving its power from running water rather than wave motion, has been built by an Arizona rancher. A main irrigation canal bordered his land, with a flow of 8 m.p.h. He constructed a raft with four 18-inch spiral rotors underneath, linked the driveshaft of each to a common shaft which drove a 32-volt generator. The motor functions with perfect satisfaction and supplies all the current consumed on the ranch. One of the accompanying drawings makes its construction clear. A similar machine can easily be constructed by anyone.

Electricity From Flowing Water

A momentum motor of this type has infinite possibilities. Imagine one with a battery of 20 spiral rotors 30 feet in diameter set in “the narrows” of the Bay of Fundy with its 60-ft. tides! Or in the St. Lawrence River or at Sault Ste. Marie! Or at numerous points in the Ohio, Missouri, Mississippi or Colorado Rivers! A momentum motor set in the Golden Gate at San Francisco without in any way impeding navigation, would develop enough power from the inflowing and outflowing tides to supply electricity to all the bay cities. As long as the tides ebb and flow, our supply of electricity will be assured.

On all sides we see examples of wasted energy—power! Think of what is wasted every day by the millions of automobiles and other moving vehicles. In an automobile, heat, the very essence of power, is wilfully wasted in enormous quantities—in the radiator and out through the exhaust pipes.

Waste Power of Automobiles

Suppose a coil of copper tubing were placed inside the exhaust manifold, and a highly volatile liquid, as ether or alcohol, were injected into this coil, wouldn’t the expanded vapor run a fairly sizeable “steam” engine? And couldn’t the vapor be condensed in a special radiator and be used over and over?

What about the energy wasted when the brakes are applied—dissipated in friction? Cruising along at 30 m.p.h.—”Stop” sign— on with the brakes. Twenty to fifty horsepower gone beyond recall.

Suppose instead of friction brakes, electrical brakes were used, and the current generated were stored in batteries, how much wasted energy could be saved?

Of course, with fuel at a reasonable price, it is not practical to make the elaborate installations necessary for conserving the wasted energy. We have one outstanding example of its being done. On the electrical section of the Chicago, Milwaukee & St. Paul railroad, when a train goes down the long grade over the Cascade mountains, the motors are converted into generators and serve as electric brakes, and at the same time push considerable current back into the line, which is utilized by another train coming up the grade. Trains are scheduled to take advantage of the electrical counterbalance.

Heat Represents Power

Heat is usually associated with all motors and engines. Somewhere in the scheme of things heat has played a part. But the generally accepted idea is that abnormal heat is required, as in the steam engine and internal combustion motor. The fact of the matter is that potential power exists wherever two masses of different temperature are available. Dr. Georges Claude demonstrated this with his remarkable vacuum, or low pressure steam turbine, down on the coast of Cuba, described in a past issue of Modern Mechanics and Inventions.

Much has been written about atomic power, the tremendous energies compacted within the atom being depicted as capable of furnishing all the power the world will ever need for billions of years. This is undoubtedly true, but scientists are by no means sanguine that a method of applying the atom’s power will ever be devised.

Sunlight Powers Automobile
POWERED by the same kind of solar cells used in space vehicles, this car—a 1912 Baker electric— has a top speed of 20 mph.

The 26 sq. ft. panel atop the car contains some 10,640 silicon cells which convert sunlight to electricity. The car was rigged with the cells merely to demonstrate the potential of solar power conversion, and the cells produce enough electricity in eight hours of sunlight to run it for only an hour.

The system was developed by Dr. Charles A. Es-coffery, technical assistant to the president of International Rectifier Corp., El Segundo, Calif. Cost of the solar cell panel is about $15,000. In mass production quantities of a hundred or so, it could be sold for $2,000 to $3,000, says Dr. Escoffery.

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New Schemes for Harnessing the Winds

INVENTORS PROPOSE STRANGE PLANS TO BRING THE OLD DUTCH MILL UP TO DATE

IS THE windmill coming back? With strange, unconventional types, inventors are seeking to adapt it to a modern age. Their experiments may bring new success in man’s effort for 800 years or more to harness the wind for power.

Centuries ago, people milled their flour, sawed wood, and pumped water with the picturesque European windmills whose enormous “sails” swept from earth to sky. This country contributed the smaller and more practical narrow-bladed type that pumps water on farms today. A new miniature design shaped like an airplane propeller charges storage batteries for radios and for lighting rural homes.

To provide power on a larger scale, giant structures envisioned by modern designers would reach heights where winds constantly blow. One inventor, Hermann Honnef, proposes to mount 500-foot wheels, with spokes that serve as vanes, upon high towers. A single “skyscraper windmill” of this type, he estimates, would generate enough electricity for a city of 100,000 inhabitants. Another designer, Peter Bendmann, offers plans for a pair of giant windmills, connected at right angles to each other and arranged to move around an endless track so as to obtain maximum power in wind from any direction.

At Burlington, N. J., recently, a spool-shaped rotor ninety feet high strained at its moorings with a ten-ton horizontal pull, when an electric motor spun it in the wind. The inventor, Julius D. Madaras, plans to mount twenty such rotors on flat cars, and make the wind propel the whole train around a circular track. Dynamos geared to the car wheels would generate many times the amount of power needed to turn the rotors, and the surplus would be marketed.

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Super-Windmills

Plans are being made to harness mankind’s oldest and cheapest source of power for industry by means of huge aerogenerators.

By Frank Tinsley

THE next few years may see a decided change in the landscape of our country. In certain strategic places which promise a constant, strong wind such as mountain passes, will grow strange structures resembling the Martian machines of H. G. Wells. But these will be instruments of construction, rather than destruction —tall, steel towers supporting fans to convert wind energy into electrical power.

Members of the Congressional Interior and Insular Affairs Committee are enthusiastic over a new proposal to erect these machines. Introduced by Representative John R. Murdock, D.,Ariz., chairman of the committee, a bill drawn up by the Department of the Interior and endorsed by the Federal Power Commission authorizes a $2,750,000 government project to build a test aerogenerator.

In 1941, a full-scale instrument was built on a mountain top in Vermont and hooked up to the high tension system of the Central Vermont Public Service Corporation as an auxiliary power source. Mounted on a 110-foot tower, its twin 56-foot blades were designed to develop 1,200 kilowatts at a wind velocity of 30 mph. Under favorable conditions, it actually developed 1,400. Although a practical success, structural and financial difficulties ended the experiment.

The newly proposed design is the product of years of research by Percy H. Thomas, well-known power plant engineer formerly of the Federal Power Commission. Towering 475 feet above the ground and equipped with a pair of three-bladed impellers, it operates automatically in a wind as light as 10 mph. At its maximum required velocity of 28 mph it delivers 7,500 kilowatts. During dangerously high winds the impeller blades can be feathered and braked to a halt and the structure is stressed to withstand hurricane velocities up to 200 mph. The plant is completely self contained with a central generator, converter, transformer, etc., mounted in a rotating housing atop the tower. The energy developed by the 150-foot diameter impellers is transmitted to the generator through geared-up shafting. All parts of the plant are accessible for inspection and repair.

The techniques of modern airplane construction suggest the possibility of further development of this design. (See illustration.) The use of light metals would lighten loads and relieve stresses. A central tubular elevator shaft would strengthen the structure, provide easier access to the operating head in foul weather and act as a protected duct for the power lines. The addition of a third impeller unit would increase the power outlet by 50 per cent while increasing the overall weight of the rotating head by but 25 per cent. Mounting small, individual generators in each impeller nacelle not only balances the weight of the wheel but also eliminates weighty, vibration-producing shaft transmissions. Instead, simple power lines are led through the pylons and elevator shaft to the ground where the heavy elements of the plant are installed in a substantial building. This placement of the generators, converters, etc., materially lightens the tower structure.

Dependent on the ever-changing wind, a single aerogenerator obviously can not be relied upon for continuous or “firm” power. However, interconnected but scattered units can maintain a firm average output. Tests indicate that wind velocities in given locations remain constant for 22 out of the 24 hours. This can be enhanced further by placing the aerogenerator groups in mountain passes where converging ranges funnel the wind flow in a strong, steady venturi effect. Such groups, acting as a free-fuel auxiliary to established steam or hydroelectric systems, may supply up to 40 per cent of the total utility power. During slack periods of consumption, this aero energy can pump used water back into reservoirs, thus storing power for future use. This means that during droughts, scarce water can be used to develop power over and over again.

As compared with complicated steam power plants and the vast sums spent on hydroelectric dams and reservoirs, the first cost of the aerogenerator is modest. Even this would be considerably reduced by the limited mass production necessary to produce a moderate number of aerogenerator complexes. Once installed, operation costs are extremely low.

European experts, working under the Marshall plan, have launched a research program to speed the harnessing of the wind for electricity. England is said to be three years ahead of us in development Recently a German engineer entered the field with a proposal to build 1,000-foot wind towers to provide power for the industrialization of Schleswig-Holtein.

Russia led the world in aerogeneration development during the 1930′s but like most other Red scientific projects its postwar status is veiled by the Iron Curtain. In her desperate effort at industrialization, she may seize the lead again. Meanwhile, with Congress now alerted to the opportunity, we can hope that America is awakening to the possibilities of this great, free source of untapped power.

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Sun Furnace Goes to Work
A man-made inferno tries out materials for jet and rocket engines—and shows one way to capture free solar power.

By Alden P. Armagnac

ATOP a 6,000-foot mountain near San Diego, Calif., they’re harnessing the sun to help build airplanes. A solar furnace newly installed there focuses the sun’s rays, with a 10-foot-diameter mirror of polished aluminum, upon a spot smaller than a dime. It surpasses by far the temperature of the hottest blowtorch or electric furnace.

Researchers of the Consolidated Vultee Aircraft Corporation apply the sun furnace’s terrific heat to materials under trial for jet and rocket engines and for guided missiles. Aim of their experiments is to develop substances more resistant to heat and thermal shock than any yet known—stuff that won’t soften and flow, say, when a long-range missile screams back to the earth from dizzy altitudes.

That the possibilities are promising is shown by recent discovery of two super-refractories, hafnium carbide and tantalum carbide, with fantastically high melting points—7,530 and 7,020 degrees F., respectively. The first looks like the record for any substance known. For comparison, iron melts at a mere 2,800 degrees, and tungsten tops the list of metals at 6,100 degrees; while graphite, long the supreme heat-resisting material, turns from solid into vapor at about 6,600 degrees.

The California experimenters’ solar furnace, essentially, an enormous burning glass, provides the most practicable way to explore this newly opening extreme-high-temperature realm. When sky conditions are ideal, it yields an estimated maximum of 8,500 degrees F. At the focus of the great mirror, this heat is concentrated in a spot 5/16 of an inch in diameter.

Metal Melts Like Butter on a Stove

Its intensity burns a hole in firebrick with ease. Steel melts and drips like sealing wax over a flame, when a rod is held with its tip at the focal point. A movable cylindrical sunshade controls the temperature of thousands of degrees to within a degree or two, a triumph of precision. Equipped with an astronomical drive, the big mirror turns automatically to follow the sun, permitting experiments of hours duration.

Best of all pure samples of materials can be subjected to the searing heat without contamination by foreign substances, like carbon in electric furnaces. And there are no electric and magnetic fields, nor fumes, to disturb reactions or hinder spectroscopic observation.

Science’s Pioneers Led Way

In going to work for industry, the solar furnace has exchanged academic robes for overalls. For its advantages long were appreciated only by savants of pure science. Lavoisier and other great chemists of the past melted metals with solar furnaces, which made up in size whatever their lenses or mirrors lacked in optical perfection. Then the idea seems to have been forgotten, until recent years.

Abroad, French experiments that began a few years ago with a 78-inch searchlight mirror (PSM, Aug. ’50, p. 122) have now led to what is probably the world’s largest solar furnace. Using a 40-foot-diameter composite mirror, a mosaic of small panes of window glass, this semi-industrial installation in the Pyrenees went into operation in 1952.

In this country, first practical use of a solar furnace appears to date back only a little earlier, to a little-known project of World War II. A 120-inch sun furnace was built for the AC Spark Plug Division of General Motors at Flint, Mich., with the cooperation of the Aluminum Company of America. Originally 16 reflecting sectors of quarter-inch sheet aluminum gave it a sa

Mounting a 98-foot wheel atop a steel tower 82 feet high, Soviet Engineers have successfully operated a 100-kilowatt wind-electric plant in the Crimean sector for more than a year. The windwheel has self-regulating variable-pitch blades which are automatically operated by centrifugal force. The Entire machine rotates on a spherical pivot in the top of the tower. The device is kept into the wind by a small motor actuate by a weather vane.

Sun’s Rays Harnessed to Run Steam Engine

One of man’s great ambitions— to harness the sun to a steam engine—has been achieved. Dr. C. G. Abbot, secretary of the Smithsonian Institution, has developed a solar heater and demonstrated that it would operate a one-half horsepower steam engine with sufficient efficiency for commercial purposes. The sun’s rays are his fuel. Caught in three parabolic cylindrical mirrors of sheet aluminum, the rays are reflected in high concentration upon tubes of Pyrex glass. Passing through two concentric tubes of glass respectively one and one-fourth and seven-eighths inch in diameter, the rays reach a central one-half inch Pyrex tube which is metal plated on top and contains a black chemical, a chlorinated diphenyl compound to which a small amount of lampblack is added so that the liquid absorbs virtually all the sun’s rays. Although liquid at ordinary temperatures, it still does not boil or flash at 662 degrees Fahrenheit. Between the concentric tubes a vacuum is maintained so that the heat of the liquid is retained. Superheated, this chemical is circulated through pipes to a boiler where it generates steam. Experimentally, this solar heat engine had an over-all efficiency of fifteen per cent in producing steam power. Dr. Abbot believes the time may come when, with coal and oil supplies dwindling, sun power may become essential. Even with the apparatus available today, he says, the sun can be harnessed for cooking, refrigeration, evaporation and small power plants. Ranches and communities in cloudless regions are manifesting interest in development of sun power.